Control valve device

ABSTRACT

An automatic-control valve device has a main valve unit, and a pilot valve unit for controlling the main valve unit. The pilot valve unit has a pilot valve A which closes when pressure in a downstream passage on the downstream side of the main valve unit increases beyond a predetermined value, a pilot valve B which opens when pressure in the downstream passage increases beyond the predetermined value. The pilot valve A and the pilot valve B are connected in series by passages through a main valve driving pressure chamber in a section between an upstream passage on the upstream side of the main valve unit and the downstream passage, and cooperate to maintain the pressure in the downstream passage at the predetermined valve. A pilot valve C which closes when the pressure difference across an orifice disposed in a passage extending through the main valve unit is greater than a predetermined value is connected in series to a passage extending across the pilot valve A to limit the flow rate of a fluid in the downstream passage to a predetermined value. The respective valve elements of the pilot valve A and the pilot valve B may be held on a single valve stem. The orifice may be of a variable type. The automatic-control valve device may be provided with a valve means placed in a passage extending across the pilot valve A to open and close the passage according to the variation of a liquid level on the downstream side, and a valve means placed in a passage extending across the pilot valve A to close the passage upon the detection of an abnormal condition by an abnormal condition detecting means.

TECHNICAL FIELD

The present invention relates to an automatic-control valve device withan automatic restriction control passage to be installed in a fluidconducting pipeline. More specifically, the present invention relates toimprovements in an automatic-control lift valve disclosed in JP-B-8-6837(hereinafter referred to as "original invention"). The present inventionintends to provide a novel valve to be used as a pressure control valveconvenient for conveying and distributing water, capable of savingmaintenance work and of being formed without difficulty in securing awatertight joint in a closed state even in a large size or high-pressurepassage, provided with a pilot valve unit omitting all elements for afixed restriction control passage, such as needle valves and cocks,having valves capable of automatically opening for self-cleaningoperation when clogged, and having functions to limit the flow of afluid automatically so that the excessive fluid may not be supplied todownstream components as well as functions of a pressure control valve.The present invention also intends to provide a convenientautomatic-control valve device capable of easily incorporating therein aliquid level control functions and emergency shutoff functions.

In this description, the term "water" is used as a general designationof fluids.

BACKGROUND ART

Generally known automatic-control valve devices prevalently used forcontrolling pressure or flow rate sense the pressure of a fluid flowingin the associated pipeline, and operate a main valve driving piston by apilot valve operated by controlling the flow rate of the fluid by afixed restriction control device, such as a needle valve. Thosegenerally known automatic-control valve devices, however, have problemsin the durability of a sealing mechanism for sealing the main valvedriving piston and in the machining accuracy of the component parts ofthe sealing mechanism. Those generally known automatic-control valvedevices need a fixed restricting device, such as a needle valve, in apassage for supplying a fluid to apply a pressure at a position on theupstream side of the main valve to the main valve driving piston todrive the main valve gradually in order that pressure pulsation due tothe sudden change of the flow of the fluid can be avoided. The fixedrestricting device, which has a minute, precision construction, isliable to be clogged with sand or dust.

The automatic-control lift valve of the original invention disclosed inJP-B-8-6837 solves those problems, is provided with a pilot valve unitnot provided with any fixed restricting device, such as a needle valve,and free from clogging, and a main valve unit capable of being easilyand simply sealed, capable of holding pressure or flow rate in a passageon the downstream side of the main valve unit at a predetermined value,and having a simple construction.

The gist of the construction of this prior art automatic-control liftvalve device mentioned in the specification are itemized as follows.

(1) In the automatic-control lift valve device as an automaticconstant-pressure valve as shown in FIG. 9, a main valve unit having amain valve casing 1 has a main valve element 5 and a main valve drivingmember 6 formed integrally with the main valve element 5, the main valvedriving member 6 is fitted for sliding movement in a chamber c definedby a cylindrical wall 8 in the main valve casing 1, the main valveelement 5 is disposed on the upstream side of a main valve opening b, apilot valve A which closes to close the main valve unit when thepressure of a fluid in a downstream passage of the main valve unit risesbeyond a predetermined level and a pilot valve B which closes to openthe main valve unit when the pressure of the fluid in the downstreampassage of the main valve unit drops below a predetermined level areconnected by a passage m connected to a main valve driving pressurechamber e formed between the main valve driving member 6 and a mainvalve top 2, and the pilot valve A and the pilot valve B are arranged inseries between an inlet passage a and an outlet passage d to make themain valve driving pressure chamber e function as an operating pressurechamber to drive the main valve unit.

(2) In the automatic-control lift valve device as an automaticconstant-flow valve device as shown in FIG. 10, a variable orifice 16 isdisposed at an appropriate position in the inlet or the outlet passageof the main valve unit operated by the pilot valves. Pressures in theupstream and the downstream side of the orifice are applied to thesecondary pressure chambers k and the spring chambers j of the pilotvalve units, respectively, to make the automatic-control lift valvedevice function as the automatic constant-flow valve.

Although the control valve device of the original invention achievesobjects satisfactorily as a constant-pressure valve or a constant-flowvalve, and is a high-performance control valve of a simple construction,problems still reside in the same control valve as considered from theviewpoint of actual working condition. When the control valve is usedpractically, actual working condition often requires the control valveto operate as a constant-pressure valve in a normal operating state andto operate as a constant-flow valve for limiting flow rate when fluidconsumption rate in the downstream passage increases excessively. Theautomatic-control valve device of the original invention is incapable ofdealing with such actual working condition alone. If theautomatic-control valve device is formed as a constant-pressure valveand the pressure in the downstream passage drops due to excessiveincrease in fluid consumption rate in the downstream passage, the mainvalve unit of the automatic-control valve exercises the originalfunction of a constant-pressure valve to compensate for the pressuredrop, whereby the function of the automatic-control valve device tomaintain the flow rate constant is spoiled. If the automatic-controlvalve device is formed as a constant-flow valve and the flow rate in thedownstream passage decreases, the main valve unit of theautomatic-control valve device exercises the original function of aconstant-flow valve to compensate for a reduction in the flow rate,whereby the function of the automatic-control valve device to maintainthe pressure constant is spoiled.

It has been considered that it is difficult to realize both the functionof a constant-pressure valve and that of a constant-flow vale by asimple construction. Therefore, it has been usual to use aconstant-pressure valve and a constant-flow valve in combination or touse a valve provided with an expensive sensors and a changeover devicefor changing the function of a constant-pressure valve for that of aconstant-flow valve and vice versa.

Accordingly, it is an object of the present invention to provide aconvenient automatic-control valve device solving the foregoing problemsresiding in the original invention, having all the advantages of theoriginal invention that the fluid does not leak at all when the mainvalve unit is closed, not provided with any fixed restricting device,such as a needle valve, and hence free from troubles due to cloggingattributable to a fixed restricting device, comprising valve unitshaving self-cleaning capability and capable of saving maintenance work,and capable of properly exercising both the function of aconstant-pressure valve and that of a constant-flow valve.

Another object of the present invention is to provide a convenientautomatic-control valve device capable of easily and simplyincorporating a liquid level control unction and an emergency shutofffunction therein.

DISCLOSURE OF THE INVENTION

With the foregoing object in view, the present invention provides anautomatic-control valve device comprising a main valve unit, and a pilotvalve unit interlocked with the main valve unit to control the mainvalve unit according to variation of pressure of a fluid flowing throughthe main valve unit;

wherein the main valve unit comprises a main valve casing, a main valveelement disposed in the main valve casing, and a main valve drivingmember disposed in the main valve casing together with the main valveelement and having a pressure receiving area greater than that of themain valve element, the main valve element is disposed on the upstreamside of a main valve seat so as to form a restricting passage betweenthe main valve element and the main valve seat, the main valve drivingmember is disposed for sliding movement in a space defined by acylindrical wall in the main valve casing so as to define a main valvedriving pressure chamber together with the cylindrical wall, an orificeis formed in a passage extending through the main valve unit; and

the pilot valve unit comprises;

a pilot valve A which is operated by a balance of forces counteractingeach other and produced respectively by a pressure in a passage on adownstream side of the main valve unit and the predetermined pressuremeans, closes when the pressure in a passage on a downstream side of themain valve unit increases beyond a predetermined level and opens whenthe same decreases below the predetermined level,

a pilot valve B which is operated by a balance of forces counteractingeach other and produced respectively by a pressure in the passage on thedownstream side of the main valve unit and the predetermined pressuremeans, opens when the pressure in the passage on the downstream side ofthe main valve unit increases beyond a predetermined level and closeswhen the same decreases below the predetermined level, and

a pilot valve C which is operated by a balance of forces counteractingeach other and produced respectively by pressure difference across theorifice and a predetermined pressure means, closes when the pressuredifference across the orifice is greater than a predetermined value andopens when the same pressure difference is smaller than thepredetermined value; and

the pilot valve A and the pilot valve B are connected in series viapassages through the main valve driving pressure chamber in a sectionbetween a passage on the upstream side of the main valve unit and apassage on the downstream side of the main valve unit, and the pilotvalve C is connected in series to passages connected to the pilot valveA.

The respective valve elements of the pilot valve A and the pilot valve Bmay be held on a single valve stem to operate both the valve elementssimultaneously by the balance of forces counteracting each other andproduced respectively by pressure in the passage on the downstream sideof the main valve unit and the predetermined pressures means.

The orifice may be of a variable type.

The automatic-control valve device may further comprise a valve meansplaced in a passage extending across the pilot valve A to open and closethe passage.

The valve means may be one that is opened and closed depending uponvariation of the liquid level on the downstream side, or may be one thatis closed upon detection of an abnormal condition by an abnormalcondition detecting means.

The predetermined pressure means may comprise an extensibledouble-cylinder case having an upper cylinder and a lower cylinder,capable of extending to a limit length limited by the engagement of theupper and the lower cylinder, and a compressed elastic member containedin the double-cylinder case.

The automatic-control valve device of the forgoing constructionexercises the following effects.

When water flows through the automatic-control valve device, pressure ina downstream passage on the downstream side of the main valve unitvaries according to the variation of fluid consumption rate in thedownstream passage, the pilot valve A which closes when pressure in thedownstream passage is higher than a predetermined level and the pilotvalve B which opens when pressure in the downstream passage is higherthan the predetermined level cooperate to maintain the pressure in thedownstream passage at a predetermined level by properly controlling thepressure in the main valve driving pressure chamber to control theopening of the main valve element.

In a state where the automatic-control valve device is operating as aconstant-pressure valve, the pilot valve C is open and does notinterfere with the functions of the constant-pressure valve provided bythe operation of the pilot valves A and B if fluid consumption rate inthe downstream passage is not higher than a predetermined value.

In a state where fluid consumption rate in the downstream passage isexcessively high and is about to exceeds the predetermined value, thepressure difference between pressures on the opposite sides of theorifice increase, the pilot valve C operates in a closing direction, thefunction of the pilot valve C takes precedence over the functions of theconstant-pressure valve to maintain fluid flow rate at the predeterminedvalue by operating the main valve element in a closing direction.

When the operation of a device on the downstream side of theautomatic-control valve device is ended and as an operation for closingan end passage continues, the pressure in the downstream passage risesaccordingly. Consequently, the pilot valve A closes and the pilot valveB opens to close the main valve element so that the pressure in thedownstream passage is maintained at the predetermined value. The flowrate decreases as the end passage is closed and the pressure differencebetween the pressures on the opposite sides of the orifice decreases.Therefore, the pilot valve C is opened and does not interfere with theoperations as a constant-pressure valve.

In the automatic-control valve device of this configuration according tothe present invention, abnormal rise in the pressure in the downstreampassage does not occur even if a sealing member combined with the mainvalve driving member is not very highly watertight. When clogged withsand or dust, the pilot valve A, the pilot valve B and the pilot valve Care capable of removing the sand or dust therefrom by a self-cleaningoperation in which the clogged valve unit is opened automatically by apressure variation resulting from the clogging of the same valve.

A float valve may be placed in the passage of the pilot valves to add aliquid level control function to the automatic-control valve device, anda valve means which closes when an abnormal condition detecting meansdetects an abnormal condition can readily by added to theautomatic-control valve device to provide an emergency shutoff functionadditionally to the automatic-control valve device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal sectional view of an automatic-control valvedevice in a first embodiment of the present invention;

FIG. 2 is a longitudinal sectional view of an automatic-control valvedevice in a second embodiment of the present invention;

FIG. 3 is a longitudinal sectional view of an automatic-control valvedevice in a third embodiment of the present invention;

FIG. 4 is a longitudinal sectional view of an automatic-control valvedevice in a fourth embodiment of the present invention;

FIG. 5 is a longitudinal sectional view of an automatic-control valvedevice in a fifth embodiment of the present invention;

FIG. 6 is a longitudinal sectional view of an automatic-control valvedevice in a sixth embodiment of the present invention;

FIG. 7 is a longitudinal sectional view of an automatic-control valvedevice in a seventh embodiment of the present invention;

FIG. 8 is a longitudinal sectional view of an automatic-control valvedevice in an eighth embodiment of the present invention;

FIG. 9 is a longitudinal sectional view of a prior art automaticconstant-pressure valve device; and

FIG. 10 is a longitudinal sectional view of a prior art automaticconstant-flow valve device.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in its preferred embodimentsshown in the accompanying drawings.

In the following description, a pilot valve A will be referred to as "Avalve", a valve element included in the A valve will be referred to as"A valve element", a pilot valve B will be referred to as "B valve", avalve element included in the B valve will be referred to as "B valveelement", a pilot valve C will be referred to as "C valve", a valveelement included in the C valve will be referred to as "C valveelement", a pressure in an upstream passage on the upstream side of amain valve unit will be referred to as "primary pressure" and a pressurein a downstream passage on the downstream side of the main valve unitwill be referred to as "secondary pressure".

Referring to FIG. 1 showing an automatic-control valve device in a firstembodiment of the present invention, a main valve unit has a main valvecasing 1 having an inlet passage a and an outlet passage d2, a mainvalve top 2, and a main valve seat 4 attached to a partition wall 3formed in the main valve casing 1. Arranged in the main valve casing 1are a main valve element 5 disposed on the upstream side of the mainvalve seat 4, a main valve driving member 6 fitted for sliding movementin a space defined by a cylindrical wall 8 formed in the main valvecasing 1 and provided with a sealing member 12 for making a sealed jointbetween the main valve driving member 6 and the cylindrical wall 8, anda main valve stem 7 holding both the main valve element 5 and the mainvalve driving member 6. The main valve stem 7 is supported for axialmovement by the main valve seat 4 facing valve legs 13, and by a bearing14. The main valve driving member 6, the cylindrical wall 8 and the mainvalve top 2 define a closed main valve driving pressure chamber e. Thepressure in the driving pressure chamber e is controlled to drive themain valve element 5 for valve opening and closing operations. Thepressure receiving area of the man valve driving member 6 is somewhatgreater than that of the main valve element 5. A sealing member 5sattached to the main valve element 5, and a sealing member 24s attachedto an A valve element 24 included in an A valve secure highly watertightsealing joints when the main valve unit is closed. Therefore, it issatisfactory if the sealing member 12 attached to the main valve drivingmember 6 is able to secure a low watertight sealing joint such that theleakage of the fluid through the watertight joint can be prevented.

An orifice 16 is disposed in a passage extending through the main valveunit. In this embodiment, the orifice 15 is of a variable type capableof being operated for flow control by operating a handwheel 17.

The A valve closes when the secondary pressure rises beyond apredetermined value and opens when the secondary pressure drops belowthe predetermined value, and the B valve opens when the secondarypressure rises beyond the predetermined value and closes when thesecondary pressure drops below the predetermined value. These A and Bvalves are connected to the main valve driving pressure chamber e via apassage m. The A valve and the B valve are connected in series to theinlet passage a and the outlet passage d2 by passages p and q2 to makethe main valve driving pressure chamber e function as an operatingpressure chamber for driving the main valve unit.

The C valve closes when the differential pressure across the orifice 16disposed in the passage of the main valve unit increases beyond apredetermined value and opens when the same drops below thepredetermined value. The C valve is placed in series to the passageacross the A valve.

Referring to FIG. 1, the A valve has a valve casing 21 provided with anA valve element chamber g, a intermediate chamber h and a secondarypressure chamber k, a valve top 22, a pressure receiving plate 23, asealing member 26, and a valve stem 25 holding both an A valve element24 and the pressure receiving plate 23. A spring 27, i.e., apredetermined pressure means, is contained in a spring chamber j definedby the valve top 22. The A valve element 24 is provided with the sealingmember 24s to secure a highly watertight sealing joint.

As shown in FIG. 1, the B valve has a valve casing 31 provided with a Bvalve element chamber i, an intermediate chamber h and a secondarypressure chamber k, a valve top 32, a pressure receiving plate 33, asealing member 36, and a valve stem 35 holding both a B valve element 34and the pressure receiving plate 33. A spring 37, i.e., a predeterminedpressure means, is contained in a spring chamber j defined by the valvetop 32. The B valve element 34 need not secure a watertight sealingjoint and may allow slight leakage when the B valve is closed.Naturally, the B valve element 34 may be provided with a sealing memberto secure a highly watertight joint.

As shown in FIG. 1, the C valve has a valve casing 41 provided with a Cvalve element chamber n and an upstream side orifice pressure chamber u,a valve top 42, a pressure receiving plate 43, a sealing member 46, anda valve stem 45 holding both a C valve element 44 and the pressurereceiving plate 43. A spring 47, i.e., a predetermined pressure means,is contained in a spring chamber j defined by the valve top 42. Thisspring chamber j also forms a downstream side orifice pressure chamberw. The C valve element 44 need not secure a watertight sealing joint andmay allow slight leakage when the C valve is closed. Naturally, the Cvalve element 44 may be provided with a sealing member to secure ahighly watertight joint.

The B valve element chamber i of the B valve is connected to the inletpassage a of the primary pressure via the passage p. The intermediatechambers h of the A valve and the B valve are connected to the mainvalve driving pressure chamber e via the passage m. The A valve elementchamber g of the A valve is connected through the C valve elementchamber n of the C valve to the outlet passage d2 of the secondarypressure by the passage q2. The secondary pressure chambers k of the Avalve and the B valve are connected to the outlet passage d2 of thesecondary pressure by the passage q2. The upstream side orifice pressurechamber u and the downstream side orifice pressure chamber w of the Cvalve are connected to an upstream side passage d1 on the upstream sideof the orifice 16 and the outlet passage d2 on the downstream side ofthe orifice by a passage q1 and the passage q2, respectively.

The operation of the invention will be described with reference to FIG.1 showing the automatic-control valve device in the first embodiment.

The automatic-control valve device shown in FIG. 1 is placed in a fluidconducting pipeline. In an initial stage of passing water through theautomatic-control valve device, the pressure in the outlet passage d2 isbelow a predetermined pressure, and the resilience of the spring 37 ofthe B valve is higher than a force resulting from the secondary pressureapplied to the secondary pressure chamber k and hence the B valveelement 34 of the B valve is seated on the valve seat to close the Bvalve. Consequently, the fluid of the primary pressure is unable to flowthrough the passage p, the B valve element chamber i, the intermediatechamber h and the passage m into the main valve driving pressure chambere of the main valve unit. Therefore, the main valve element 5 is forcedto move gradually from a fully closed position toward a fully openposition by a force produced by a pressure difference corresponding tothe difference in pressure receiving area between the main valve drivingmember 6 and the main valve element 5 to allow the fluid to flow throughthe passages a, b, d1 and d2. Thus, the main valve unit exercises anexcellent operating characteristic to avoid abnormal rise in thesecondary pressure even if the water pump or the like is started upsuddenly.

After the secondary pressure in the outlet passage d2 has increased to apredetermined level, the valve elements 24 and 34 of the A valve and theB valve move according to the variation of the secondary pressure due tothe variation of fluid consumption rate in the downstream passage toregulate the position of the main valve element 5 by properly regulatingthe pressure in the main valve driving pressure chamber e so that thepredetermined secondary pressure is maintained.

In this state where the automatic-control valve device is thusfunctioning as a constant-pressure valve, the resilience of the spring47 of the C valve is higher than a force corresponding to the pressuredifference across the orifice 16 if the fluid consumption rate in thedownstream passage is below a predetermined limit and hence the C valveelement 44 of the C valve is at a fully open position and the C valvedoes not affect the flow of the fluid through the A valve and the Bvalve into the passage q2; that is, the C valve does not interfere withthe function of the automatic-control valve device as aconstant-pressure valve.

If the fluid consumption rate in the downstream passage is excessivelyhigh and is almost exceeding the predetermined limit, the pressuredifference across the orifice 16 rises according to the increase of thefluid consumption rate in the downstream passage, and a force resultingfrom the pressure difference acting on the pressure receiving plate 43of the C valve exceeds the resilient of the spring 47. Consequently, theC valve element 44 is moved in a closing direction to reduce thesectional area of the passage connected to the passage q2, i.e., the Cvalve interferes with the operation of the automatic-control valvedevice as a constant-pressure valve, and the pressure in the main valvedriving pressure chamber e of the main valve unit increases toward theprimary pressure. Then, the main valve element 5 is moved in a closingdirection by the difference between pressures acting on the front andthe back surface thereof, respectively, so that the main valve opening bis reduced to maintain the flow rate of the fluid flowing through themain valve unit at the predetermined value.

The secondary pressure can be set to a predetermined value simply byadjusting the respective resiliences of the springs 27 and 37 of the Avalve and the B valve by operating adjusting screws, respectively. Theflow of the fluid can be adjusted to a desired flow rate by adjustingthe position of the orifice 16 by operating the handwheel 17.

When the use of the fluid in the downstream passage is ended and anoperation to close a downstream passage is started, the secondarypressure rises accordingly, the forces corresponding to the secondarypressure acting on the respective pressure receiving plates 23 and 33 ofthe A valve and the B valve exceeds the respective resiliences of thesprings 27 and 37. Consequently, the A valve element 24 is fully closedand the B valve element 34 is fully opened, so that the pressure in themain valve driving pressure chamber e increases toward the primarypressure, and the main valve element 5 is moved in a closing directionby the difference between thrusts acting respectively on the front andthe back surface of the main valve element 5. As a result, the mainvalve opening b is closed, and the predetermined secondary pressure ismaintained.

The pressure difference across the orifice 16 decreases as the flow rateof the fluid decreases with the closing of the downstream passage.Consequently, the resilience of the spring 47 of the C valve exceeds aforce corresponding to the pressure difference across the orifice 16,and the C valve element 44 of the C valve is returned to its fully openposition. In this state, the C valve does not interfere with theoperation of the automatic-control valve device as a constant-pressurevalve.

The sealing member 5s put on the main valve element 5 and the sealingmember 24s put on the A valve element 24 must secure a perfectwatertight joint in a state where the main valve unit is closedcompletely. The sealing members 5s and 24s are able to secure awatertight joint easily by a conventional technique. The sealing member12 put on the main valve driving member 6 is difficult to fabricate withprecision. However, the fluid will not leak from the upstream side intothe downstream side and the abnormal rise of the secondary pressure willnot occur even if the sealing member 12 forms a rough watertight joint.

Since the pilot valves, i.e., the A valve, the B valve and the C valve,are not provided with any fixed restricting device, such as a needlevalve, the pilot valves are rarely clogged with sand or dust. Even ifany one of the main valve unit, the A valve, the B valve and the C valveshould be clogged, the clogged valve is caused to open automatically bya change in the fluid pressure caused by the clogged valve and theclogged valve is able to exercise its self-cleaning function to removesand or dust clogging the same. Accordingly, the automatic-control valvedevice need not be provided with a strainer of a fine mesh or the like,which makes the maintenance of the automatic-control valve device easy.

Automatic-control valve devices in second to eighth embodiments of thepresent invention will be described with reference to FIGS. 2 to 8, inwhich like or corresponding parts are designated by the same referencecharacters.

As shown in FIG. 2, the automatic-control valve device in the secondembodiment has an A.B compound valve, which is a combination of the Avalve and the B valve employed in the first embodiment. The A.B compoundvalve has a cylinder-piston valve operating mechanism formed by mountingan A valve element 24 and a B valve element 34 on a single valve stem25, and the valve stem 25 is operatively connected to a singlepredetermined pressure means (spring 27). The A.B compound valve is soformed that the A valve element 24 and the B valve element 34 may notobstruct each other. Both the A valve element 24 and the B valve element34 are at a substantially close deposition while the secondary pressureis stable. Although the second embodiment employing the A.B compoundvalve formed by combining the A valve and the B valve of the firstembodiment differs somewhat in the arrangement of passages from thefirst embodiment, the second embodiment is similar in other respects,functions and effects to the first embodiment, and hence the furtherdescription thereof will be omitted.

As shown in FIG. 3, the automatic-control valve device in the thirdembodiment has an A.B.C compound valve, which is a combination of the Avalve, the B valve and the C valve employed in the first embodiment. AnA valve element 24 and a B valve element 34 are mounted on a valve stem25, and a C valve element 44 is mounted on a valve stem 45. The valvestems 25 and 45 are able to move independently. Although the thirdembodiment employing the A.B.C compound valve formed by combining the Avalve, the B valve and the C valve of the first embodiment differssomewhat in the arrangement of passages from the second embodiment, thethird embodiment is similar in other respects, functions and effects tothe second embodiment, and hence the further description thereof will beomitted.

In the automatic-control valve device shown in FIG. 3, the resilience ofa spring 47, i.e., a predetermined pressure means, included in the Cvalve can be adjusted by means of an adjusting screw. The flow rate ofthe fluid can be adjusted to a predetermined fixed value by operating anorifice 16 by means of a handwheel 17 or the like to adjust restrictionand the fine adjustment of the flow rate can be achieved simply byadjusting the resilience of the spring 47 by means of the adjustingscrew.

As shown in FIG. 4, the automatic-control valve device in the fourthembodiment has an orifice 16 placed between passages a1 and a2 on theupstream side of a main valve unit. The position of the orifice 16 isopposite to that of the orifice 16 of the third embodiment with respectto the main valve unit. Although the fourth embodiment differs in thearrangement of the orifice 16 from the third embodiment, and hence thearrangement of passages such as p1 and p2 is somewhat difference fromthat in the third embodiment accordingly, the fourth embodiment issimilar in other respects, functions and effects to the thirdembodiment, and hence the further description thereof will be omitted.

As shown in FIG. 5, the automatic-control valve device in the fifthembodiment has a main valve driving member 6 disposed on the downstreamside of a main valve seat 4. The disposition of the main valve drivingmember 6 is opposite to that of the main valve driving member 6 in thefourth embodiment with respect to the main valve seat. Althoughdirections of movement of the main valve driving member 6 in the fifthembodiment are opposite to those of the main valve driving member 6 inthe fourth embodiment and the arrangement of passages connecting the Avalve and the B valve to an inlet passage a2 and an outlet passage d isreverse to that of the passages in the fourth embodiment, the fifthembodiment is similar in other respects, functions and effects to thefourth embodiment, and hence the further description thereof will beomitted.

As shown in FIG. 6, the automatic-control valve device in the sixthembodiment has an A.B.C compound valve similar to that employed in thefourth embodiment, in which both an A valve element 24 and a B valveelement 34 are contained in an intermediate chamber h and thearrangement of passages in the sixth embodiment differs somewhat fromthat of the passages in the fourth embodiment. However, the sixthembodiment is similar in other respects, functions and effects to thefourth embodiment. As shown in FIG. 6, a predetermined pressure means(spring 27) included in the A.B.C compound valve is contained in atelescopic double-cylinder case 28 consisting of an upper cylinderhaving a stopper 28b, and a lower cylinder having a stopper 28a whichengages with the stopper 28b to limit the extension of the telescopicdouble-cylinder case 28.

As shown in FIG. 7, the automatic-control valve device in the seventhembodiment has an A.B.C compound valve similar to that employed in thefourth embodiment, in which a C valve is connected to a float valve 51disposed at a level near the liquid level in a downstream passageinstead of connecting the same directly to an outlet passage d of thesecondary pressure. The float valve 51 opens when the liquid level inthe downstream passage is not higher than a predetermined level to allowthe fluid to flow through the passage connected thereto and closes whenthe liquid level rises to the predetermined level. The float valve 51shown in FIG. 7 is of a common type. The seventh embodiment is similarin other respects, functions and effects to the fourth embodiment.

When the A.B.C compound valve is connected to the float valve 51disposed at a level near the liquid level in a downstream passageinstead of connecting the same by a passage to the outlet passage d, theautomatic-control valve device operates as a constant-pressureconstant-flow valve and varies the flow rate of the fluid linearlyaccording to the variation of the liquid level. Therefore, the fluid isdischarged properly and the fluid is not supplied excessively even ifthe pressure in the inlet passage is high. The float valve 51 closesupon the rise of the liquid level to the predetermined level, and thepressure in a main valve driving pressure chamber e rises. Consequently,a main valve element 5 is seated automatically on a main valve seat anda sealing member 5s put on the main valve element 5 and a sealingmember, now shown, included in the float valve 51 secure watertightjoints, respectively.

The float valve may be of any suitable one of conventional types, suchas a ball-tap type. Naturally, the float valve controlled by a float maybe substituted by a valve means controlled by a liquid level sensor. Thefloat valve may be provided in series to the C valve or may be providedin any way suitable for the installation site, instead of the manner ofinstallation according to this embodiment.

As shown in FIG. 8 an automatic-control valve device in the eighthembodiment is provided with a replaceable fixed orifice 16 instead ofthe orifice 16 employed in the fourth embodiment. A fixed flow rate isset by adjusting a spring 47.

In the eighth embodiment, a C valve is connected to an outlet passage dof the secondary pressure on the downstream side of a main valve unitthrough a valve means 53 capable of being closed upon the occurrence ofan abnormal condition by an abnormal condition detecting means 52capable of detecting abnormal conditions which occur in the environmentinstead of directly connecting the same to the outlet passage d of themain valve unit. Thus, the automatic-control valve device is providedwith an additional function as an emergency shutoff valve which closesthe associated pipeline automatically in an emergency, such as in caseof a fire, an earthquake or abnormal increase of the pressure in thepipeline. The valve means 53 controls the main valve unit to shut off ina similar manner as is done by the float valve 51 in the seventhembodiment. The valve means 53 and the abnormal condition detectingmeans 52 may be linked by a well-known linking system, such as anelectric system which drives the valve means 53 by electric signalsgenerated by sensors or a mechanical system mechanically interlockingthe valve means 53 and the abnormal condition detecting means 52, andhence the description thereof will be omitted. The eighth embodiment issimilar in other respects, functions and effect to the fourthembodiment.

Technical features common to the foregoing embodiments will be describedbelow.

In any one of the embodiments shown in FIGS. 2 to 8, both the A valveelement 24 and the B valve element 34 are mounted on the single stem 25in an axial arrangement to combine the primary pressure and thesecondary pressure in the compound valve by simultaneously moving the Avalve element 24 and the B valve element 34 and to deal quickly with thevariation of the flowing condition of the fluid by applying a combinedpressure produced by combining the primary pressure and the secondarypressure to the main valve driving pressure chamber e. Thus, theautomatic-control valve devices in the foregoing embodiments are formedin reasonable, economically effective constructions, respectively. Theautomatic-control valve devices in these embodiments, similarly to theautomatic-control valve device in the first embodiment shown in FIG. 1,employs the cylinder-piston valve operating mechanism to prevent the Avalve element 24 and the B valve element 34 from obstructing each other.The A valve element 24 and the B valve element 34 are arranged atpositions and at an interval to enable the A valve element 24 and the Bvalve element 34 to create both a condition where one of the A valveelement 24 and the B valve element 34 is at a valve opening position andthe other is at a valve closing position, and a condition where both theA valve element 24 and the B valve element 34 are substantially at avalve closing position. Both the A valve element 24 and the B valveelement 34 are substantially at the valve closing position while thesecondary pressure is stable. Accordingly, the chattering and thehunting, i.e., vibrations, of the A valve element 24 and the B valveelement 34 can be avoided.

In the automatic-control valve device shown in FIG. 6, both the A valveelement 24 and the B valve element 34 are contained in the intermediatechamber h. The relative positions of the chambers g, h, i, j, k, n, uand w, the combination of the same, and the arrangement of the passagesmay be changed within the scope of the present invention and the presentinvention is not limited in its practical application to the foregoingembodiments.

FIG. 1 shows, by way of example, a pressure balancing device 39 forequalizing slightly different pressures acting on the pilot pressurereceiving plate 33.

The embodiments shown in FIGS. 1 to 8 employ the springs 27, 37 and 47as the predetermined pressure means for the pilot valve. Indicated at28, 38 and 48 are telescopic double-cylinder cases each for containingthe spring. FIG. 6 illustrates the construction of the telescopicdouble-cylinder case in detail. The spring 27 is contained in thetelescopic double-cylinder case 28 consisting of the upper cylinder anda lower cylinder. In the state shown in FIG. 6, the stopper formed onthe outer circumference of a lower end part of the upper cylinder andthe stopper formed on the inner circumference of an upper end part ofthe lower cylinder are at positions immediately before positions wherethe same are engaged to limit the extension of the telescopicdouble-cylinder case 2, and the resilience of the spring 27 is exertedon the pressure receiving plate 23. Since the extension of thetelescopic double-cylinder case is limited, the spring can be compressedin the telescopic double-cylinder case so that sufficient energy isstored by the spring. The telescopic double-cylinder case can be easilycarried around as a module to be incorporated into the valve forassembling the valve and for the maintenance of the valve. Since thespring can be sufficiently compressed in the telescopic double-cylindercase and can be used in a range of length variation in which theresilience of the same varies in a narrow range, the valve is able tooperate accurately. Needless to say, the case may be omitted and onlythe spring may be used if the valve is used under not very severeworking conditions.

The predetermined pressure means may use, instead of an elastic member,such as the spring employed in the foregoing embodiments, for example, aweight which exerts a constant force, may be provided with an assistingservomechanism and may be a pneumatic or hydraulic mechanism. Thesealing members 26, 36 and 46 combined with the pressure receivingplates 23, 33 and 43 for securing a watertight joint may be diaphragmsas those employed in the foregoing embodiments, bellows, or O rings puton the sliding surfaces of the pressure receiving members.

Each of the main valve units employed in the foregoing embodiments is alift valve provided with the axially movable main valve element 5. Avalve other than the lift valve, such as a butterfly valve, a gate valveor a ball valve, may be used. Naturally, the main valve element 5 may beformed integrally with the main valve driving member 6. Although it isdesirable, in view of stabilizing the operation of the main valveelement 5 in an initial period of passing the fluid through theautomatic-control valve device, to provide the automatic-control valvedevice with a main valve spring 11 as illustrated in FIG. 5, the mainvalve spring 11 may be omitted because the main valve spring 11 does nothave any particular effect on the operation of the main valve element 5after the elapse of the initial period. The main passage a.b.d in themain valve unit, and the main valve driving pressure chamber e areformed in a compact arrangement in the main valve casing 1 in each ofthe automatic-control valve devices in the foregoing embodiments tosimplify the construction of the main valve unit. The main passage andthe main valve driving pressure chamber e may be formed in two separatemain valve casings, respectively, and the main valve element 5 and themain valve driving member 6 may be fixedly held on the opposite endparts of a main valve stem extending through the two main valve casing.

The valve elements of the main valve unit and the pilot valve unit arerequired to operates gradually under some conditions of use. In theautomatic-control valve devices illustrated in FIGS. 1 to 8, the mainvalve opening b is formed in a sawtooth passage to make the flow ratevary smoothly, and the main valve unit is provided with a dampingmechanism comprising a damping cylinder 9 and a piston 10 to prevent theeffects of pressure pulsation resulting from sudden change of flow, suchas chattering of the valve element. Needless to say, the secondarypressure passage connected to the secondary pressure chamber k may beprovided with a restrictor, not shown, and the pilot valves may beprovided with a damping mechanism for the foregoing purpose. Thosemethods of preventing the effects of pressure pulsation may beindividually employed, may be employed in combination, or may be omittedif the automatic-control valve device is used under conditions notrequiring such methods.

The orifice 16 may be a generally known valve, such as a butterflyvalve, a gate valve, a ball valve or a lift valve. Since the orifice 16need not necessarily be able to shut the passage in a watertightfashion, the valve seat of the orifice 16 need not necessarily beprovided with a sealing member. The orifice 16 may be operated byoperating the handwheel 17 by hand or may be operated by an actuator.Needless to say, the orifice may be operated by an automatic drivingprocedure.

The orifice 16 is disposed on the downstream side of the main valve unitin the automatic-control valve devices shown in FIGS. 1 to 3, and theorifice 16 is disposed on the upstream side of the main valve unit inthe automatic-control valve devices shown in FIGS. 4 to 8. Basically,the orifice may be disposed either the upstream side or the downstreamside of the main valve unit. It is desirable to dispose the orifice 16on the downstream side of the main valve unit in view of the capabilityof easily reducing a design pressure to be applied to the C valve. It isdesirable to dispose the orifice 16 on the upstream side of the mainvalve unit with the aim to reducing the effect of pressure pulsationresulting from the operation of the main valve element 5 on the C valve.

When the predetermined pressure means (spring 47) of the C valve isprovided with the adjusting mechanism as shown in FIGS. 3 to 8, a meansfor adjusting the flow rate of the fluid is not limited to theadjustment of the orifice 16 because the adjustment of the predeterminedpressure is equivalent to the setting of a flow rate. A flow rate may beset only through the operation of the adjusting mechanism for adjustingthe predetermined pressure means of the C valve and a fixed orifice asillustrated in FIG. 8 may be employed as the orifice 16. The use of afixed orifice is effective particularly when it is desired to reducemeasuring errors in the measurement of the pressure difference acrossthe orifice attributable to turbulent flows to the least possibleextend. Subjecting the pressure difference across the orifice toturbulent flows can be avoided by forming grooves in parts of the fixedorifice around the front and the back pressure measuring opening, whichis a well-known method and hence the description thereof will beomitted.

The sealing members put on the components of the main valve unit and thepilot valve unit to secure a watertight joint may be O-rings, oil seals,diaphragms or bellows. If a satisfactory watertight joint can be securedby the direct contact of the mating parts, the sealing member may beomitted. The valve elements of the main valve unit (combination of amain valve and an orifice) and the pilot valve unit or the valve seatsfor those valve elements may be provided with protrusions similar to theteeth of a comb or a honeycomb to prevent cavitation or the like. Asafety valve 18 may be connected to a part of the main valve unit at aproper downstream position on the main valve unit as shown in FIG. 6 ofthe safety management of the associated facilities.

There is no reason for inhibiting the application of conventionaltechniques to the component parts of the valves of the presentinvention. The present invention is not limited in its practicalapplication to the foregoing embodiments specifically described herein,and many changes and variations may be made therein without departingfrom the scope and spirit of the invention.

INDUSTRIAL APPLICABILITY

The automatic-control valve device according to the present invention isa convenient, maintenance-free valve device having the pilot valve unitnot provided with any fixed restricting devices, such as needle valves,free from troubles resulting from the clogging of the valves with sandand/or dust because the valve elements are able to open properly forself cleaning when necessary, capable of securing perfect watertightjoints when the automatic-control valve device is closed, provided withthe pressure adjusting mechanism capable of operating without causingthe abnormal rise of the secondary pressure in both a state where theautomatic-control valve device is open and a state where the same isclosed, and capable of automatically limiting the flow rate to apredetermined value. A liquid level control function and an emergencyshutoff function can be readily incorporated into the automatic-controlvalve device. The pilot valve unit has a simple construction, thesecondary pressure and the flow rate can be set by simple settingoperations. The automatic-control valve device has neither componentparts nor devices that will impose difficulties on designing,manufacturing, operating and maintaining the same. Thus, theautomatic-control valve device of the present invention is highlyreliable and highly economically effective.

What is claimed is:
 1. An automatic-control valve device comprising amain valve unit, and a pilot valve unit interlocked with the main valveunit to control the main valve unit according to variation of pressureof a fluid flowing through the main valve unit;wherein the main valveunit comprises a main valve casing, a main valve element disposed in themain valve casing, and a main valve driving member disposed in the mainvalve casing together with the main valve element and having a pressurereceiving area greater than that of the main valve element; the mainvalve element is disposed on an upstream side of a main valve seat so asto form a restricting passage between the main valve element and themain valve seat; the main valve driving member is disposed for slidingmovement in a space defined by a cylindrical wall in the main valvecasing so as to define a main valve driving pressure chamber togetherwith the cylindrical wall, an orifice is formed in a passage extendingthrough the main valve unit; and the pilot valve unit comprises;a pilotvalve A which is operated by a balance of forces counteracting eachother and produced respectively by pressure in a passage on a downstreamside of the main valve unit and a first predetermined pressure means,closes when pressure in the passage on the downstream side of the mainvalve unit increases beyond a predetermined level and opens when thesame decreases below the predetermined level, a pilot valve B which isoperated by a balance of forces counteracting each other and producedrespectively by pressure in the passage on the downstream side of themain valve unit and a second predetermined pressure means, opens whenpressure in the passage on the downstream side of the main valve unitincreases beyond a predetermined level and closes when the samedecreases below the predetermined level, and a pilot valve C which isoperated by a balance of forces counteracting each other and producedrespectively by pressure difference across the orifice and a thirdpredetermined pressure means, closes when pressure difference across theorifice is greater than a predetermined value and opens when the samepressure difference is smaller than the predetermined value; and thepilot valve A and the pilot valve B are connected in series via passagesthrough the main valve driving pressure chamber in a section between apassage on the upstream side of the main valve unit and a passage on thedownstream side of the main valve unit, and the pilot valve C isconnected in series to passages connected to the pilot valve A.
 2. Theautomatic-control valve device according to claim 1, wherein the pilotvalve A and the pilot valve B are provided, respectively, with valveelements held on a single valve stem to operate both the valve elementssimultaneously by the balance of forces counteracting each other andproduced respectively by pressure in the passage on the downstream sideof the main valve unit and the predetermined pressure means.
 3. Theautomatic-control valve device according to claim 1, wherein the orificeis of a variable type.
 4. The automatic-control valve device accordingto claim 1, further comprising a valve means placed in a passageextending across the pilot valve A to open and close the passage.
 5. Theautomatic-control valve device according to claim 4, wherein said valvemeans opens and closes according to variation of a liquid level on thedown stream side.
 6. The automatic-control valve device according toclaim 4, wherein said valve means is closed upon detection of anabnormal condition by an abnormal condition detecting means.
 7. Theautomatic-control valve device according to claim 1, wherein thepredetermined pressure means comprises an extensible double-cylindercase having an upper cylinder and a lower cylinder, capable of extendingto a limit length limited by the engagement of the upper and the lowercylinder, and a compressed elastic member contained in thedouble-cylinder case.
 8. The automatic control value device according toclaim 1 wherein the first and second predetermined pressure means areprovided by a common device.
 9. The automatic control value deviceaccording to claim 8 wherein the common device is a spring.
 10. Anautomatic-control valve device comprising a main valve unit, and a pilotvalve unit interlocked with the main valve unit to control the mainvalve unit according to variation of pressure of a fluid flowing throughthe main valve unit;wherein the main valve unit comprises a main valvecasing, a main valve element disposed in the main valve casing, and amain valve driving member disposed in the main valve casing togetherwith the main valve element and having a pressure receiving area greaterthan that of the main valve element; the main valve element is disposedon an upstream side of a main valve seat so as to form a restrictingpassage between the main valve element and the main valve seat; the mainvalve driving member is disposed for sliding movement in a space definedby a cylindrical wall in the main valve casing so as to define a mainvalve driving pressure chamber together with the cylindrical wall, anorifice is formed in a passage extending through the main valve unit;and the pilot valve unit comprises;a first pilot valve which is operatedby a balance of forces counteracting each other and producedrespectively by pressure in a passage on a downstream side of the mainvalve unit and a first predetermined pressure, said first pilot valveclosing when pressure in the passage on the downstream side of the mainvalve unit increases beyond a predetermined level and opening when thesame decreases below the first mentioned predetermined level, a secondpilot valve which is operated by a balance of forces counteracting eachother and produced respectively by pressure in the passage on thedownstream side of the main valve unit and a second predeterminedpressure, said second pilot valve opening when pressure in the passageon the downstream side of the main valve unit increases beyond apredetermined level and closes when the same decreases below the secondmentioned predetermined level, and a third pilot valve which is operatedby a balance of forces counteracting each other and producedrespectively by pressure difference across the orifice and a thirdpredetermined pressure, said third pilot valve closing when pressuredifference across the orifice is greater than a predetermined value andopening when the same pressure difference is smaller than thepredetermined value; and the first pilot valve and the second pilotvalve are connected in series via passages through the main valvedriving pressure chamber in a section between a passage on the upstreamside of the main valve unit and a passage on the downstream side of themain valve unit, and the third pilot valve is connected in series topassages connected to the first pilot valve.
 11. The automatic controlvalve device according to claim 10 wherein the first and secondpredetermined pressure are provided by a common device and wherein thefirst and second mentioned predetermined pressures are a commonpressure.
 12. The automatic control valve device according to claim 11wherein the common device is a spring.
 13. An automatic-control valvedevice comprising a main valve unit, and a pilot valve unit interlockedwith the main valve unit to control the main valve unit according tovariation of pressure of a fluid flowing through the main valveunit;wherein the main valve unit comprises a main valve casing, a mainvalve element disposed in the main valve casing, and a main valvedriving member disposed in the main valve casing together with the mainvalve element and having a pressure receiving area greater than that ofthe main valve element; the main valve element is disposed on anupstream side of a main valve seat so as to form a restricting passagebetween the main valve element and the main valve seat; the main valvedriving member is disposed for sliding movement in a space defined by acylindrical wall in the main valve casing so as to define a main valvedriving pressure chamber together with the cylindrical wall, an orificeis formed in a passage extending through the main valve unit; and thepilot valve unit comprises;a first pilot valve which is operated by abalance of forces counteracting each other and produced respectively bypressure in a passage on a downstream side of the main valve unit and apredetermined pressure, said first pilot valve closing when pressure inthe passage on the downstream side of the main valve unit increasesbeyond a predetermined level and opening when the same decreases belowthe first mentioned predetermined level, a second pilot valve which isoperated by a balance of forces counteracting each other and producedrespectively by pressure in the passage on the downstream side of themain valve unit and said predetermined pressure, said second pilot valveopening when pressure in the passage on the downstream side of the mainvalve unit increases beyond the predetermined level and closes when thesame decreases below the second mentioned predetermined level, and athird pilot valve which is operated by a balance of forces counteractingeach other and produced respectively by pressure difference across theorifice and a predetermined pressure source, said third pilot valveclosing when pressure difference across the orifice is greater than apredetermined value and opening when the same pressure difference issmaller than the predetermined value; and the first pilot valve and thesecond pilot valve are connected in series via passages through the mainvalve driving pressure chamber in a section between a passage on theupstream side of the main valve unit and a passage on the downstreamside of the main valve unit, and the third pilot valve is connected inseries to passages connected to the first pilot valve.